Effect of Delayed Input on Wide Area Optimal Control and Design of Compensation

The recent advances in wide-area measurement system (WAMS) is driving power systems to the trend of wide-area monitoring and control. In this trend, the impact of time delays introduced by remote signal transmission and processing in WAMS has to be considered. This paper will thoroughly analyze the effect of wide area linear optimal control (WALOC) with delayed remote input on inter-area oscillation damping. Eigenvalue analysis demonstrates that delay in time will cause lag in phase with respect to frequency of oscillatory mode and amplification in gain with respect to damping of oscillatory mode. The effect might drive eigenvalues of system matrix to undesirable places on complex plane, and even make power system unstable. Compensation block consisted of lead/lag module and gain module is designed to diminish the effect of time delay. Simulations on 2-machine test system are performed to substantiate obtained results and demonstrate the advantage of designed delay compensator when the time delays are within a certain range.